The main purpose of this research project is to study the electrophysiology and integrative functions of two or three electronically coupled neurons in the abdominal ganglion of Aplysia. The main interneuron L10 which has input on a large number of motor neurons in the abdominal ganglia, also is electrically coupled to two other neurons, L20 and L21. The integrative functions of L20, which sends its axon into the left pleuroviscial connective is known in so far as it differentially modulates transmitter release of transmitting different branches of L10. L21 has input in a number of the follower neurons of L10 and its activation causes a prolonged and intense hyperpolarization in these neurons. In the context of this background the following experiments are planned: 1. Recording from and stimulation of L20, while cells in the pedal, pleural, cerebral and buccal ganglia are being recorded from, to see whether L has any inputs on these cells or whether these cells have inputs on L20. 2. Recording from L10, L20 and follower neuron of L10 such as L5, while the ganglia is being perfused in tetrotoxin containing sea water. Depolarization of L20 with various current intensities and pulse shapes will be carried out to see whether spikeless release of transmitter can be induced in some branches of L10.